Research findings cast doubt on the value of conventional patrol and have allowed police managers more flexibility in constructing and testing alternative patrol strategies. They have helped police administrators understand the benefits of proactive and reactive policies. Research has also highlighted the importance of citizens in reporting crime and in providing the evidence needed to arrest and convict offenders. In addition, research has identified the existence of career criminals and has provided information about the patterns of their criminality. Moreover, research has demonstrated that police arrests in cases of spouse abuse can reduce future violence. The demand for solid, rigorous, and nonpartisan criminal justice research will continue to grow. Credible research is needed to help policymakers deal systematically with issues currently being debated and to quantify the effects of various policy choices. Footnotes and 19 references.